Cassini Significant Events 11/28/2012 – 12/04/2012

Cassini is orbiting Saturn with a period of 13.3 days and inclined 53 degrees from the equatorial plane. The most recent spacecraft tracking and telemetry data were collected on Dec. 5 by the Deep Space Network's 70 meter Station 14 at Goldstone, California. Except for some science instrument issues described in previous reports, the spacecraft continues to be in an excellent state of health with all of its subsystems operating normally. Information on the present position of the Cassini spacecraft may be found on the "Present Position" page at: http://saturn.jpl.nasa.gov/mission/presentposition/.

Thursday's T-88 encounter provided close scrutiny of Titan while giving Cassini another gravity assist to bring its orbital inclination up to 53 degrees from Saturn's equatorial plane. This was the sixth consecutive increase in inclination; after two more Titan flybys, Cassini will be up to its maximum inclination in this mission phase of 61.7 degrees. This set of inclined orbits was designed for high quality occultations of Saturn and optical remote-sensing observations that look "down" on the rings.

Wednesday, Nov. 28 (DOY 333)

Inclined orbits also provide good views of Saturn's polar regions. A series of three remarkable images that were featured today zoom in on a complex storm centered on the north pole.

Inbound to Titan, the Composite Infrared Spectrometer (CIRS) observed in the far-infrared (IR) to gather information on carbon monoxide, hydrogen cyanide, and methane in the atmosphere, and in the mid-IR to obtain vertical profiles of temperatures in the stratosphere. These and other ORS observations continued as Titan loomed closer the next day.

Seasonal changes in Titan's atmosphere are the subject of an illustrated feature released today. "NASA's Cassini Sees Abrupt Turn in Titan's Atmosphere" may be seen here: https://www.jpl.nasa.gov/news/news.php?feature=3601

Thursday, Nov. 29 (DOY 334)

Today was the only day this week that the Deep Space Network (DSN) didn't track Cassini. Using thrusters for attitude control near closest approach, the spacecraft spent the day rotating about its three axes, pointing instruments and recording data during the Titan flyby; of note, the Visible and Infrared Mapping Spectrometer (VIMS) made some particularly high-resolution observations. More details about the T-88 close encounter may be seen here: http://saturn.jpl.nasa.gov/mission/flybys/titan20121129/. In addition to the remote-sensing observations, the Magnetometer Subsystem (MAG) made observations in the post-noon sector of Saturn's magnetosphere, measuring the diffusion of the magnetic field at low latitudes and high solar zenith angles.

Friday, Nov. 30 (DOY 335)

MAG performed a calibration by rolling the spacecraft about its Z axis while Cassini carried out communications via the DSN. Following this, CIRS obtained data on the thermal structure of Titan's stratosphere.

Saturday, Dec. 1 (DOY 336)

ISS monitored Titan for an extra day after the encounter to track clouds and monitor their evolution. VIMS rode along, taking data while ISS controlled pointing.

Sunday, Dec. 2 (DOY 337)

Leaving Titan in the distance once again, CIRS started a twelve-hour observation to measure oxygen compounds (water and carbon dioxide) in Saturn's stratosphere. ISS then made observations in the Satellite Orbit Campaign, looking near Saturn to improve knowledge of small satellites' orbits or make new discoveries, and made more observations in the ring propeller tracking campaign (see http://go.usa.gov/YyGR).

Orbit Trim Maneuver 338, the post-T-88 trajectory cleanup maneuver, was performed today using the Reaction Control Subsystem thrusters. The 22.5 second burn provided a delta-V of about 28 millimeters per second.

Monday, Dec. 3 (DOY 338)

The Attitude and Articulation Control Subsystem (AACS) team executed a Reaction Wheel Assembly bias maneuver to adjust wheel speeds, while thrusters stabilized the spacecraft and the Deep Space Network (DSN) was tracking. Cassini remained Earth-pointed while the flight team began uplinking new flight software, AACS version A8.9.0.

Having coasted to an altitude of 1.7 million kilometers from Saturn, Cassini passed through apoapsis going 10,906 kilometers per hour with respect to the planet. This marked the start of Cassini's 176th orbit of Saturn.

An image of Tethys was featured today that shows its largest impact crater bisected by the day-night terminator. "Another Death Star?" may be seen here: /resources/15680.

Tuesday Dec. 4 (DOY 339)

ISS observed the irregular moon Kiviuq for ten hours. This reddish body is about 16 kilometers in diameter and orbits about 11 million kilometers from Saturn. VIMS did a Saturn storm-watch observation, and then ISS made another observation in the Satellite Orbit Campaign. Finally, VIMS began a 15 hour watch while the red-giant star R Lyrae was occulted by the rings.

A mission planning meeting was held today to review propellant use and status of the propellant budgets. A consumables status is provided on a regular basis so the Project can maintain cognizance of end-of-mission margins.

NASA's Astronomy Picture of the Day for today was one of the three polar storm images mentioned above. The page may be found here: http://apod.nasa.gov/apod/ap121204.html